The present invention is related to a control device of a bicycle gear change. In particular, the invention is directed to control devices of known type comprising:
a support body intended to be fixed onto the handle bar of the bicycle, PA1 a gear change operating rotor, rotatably mounted in the support body and carrying winding up means for a gear change flexible control cable, PA1 indexing means carried by the operating rotor and by the support body and adapted to cooperate therebetween so as to define a plurality of steady positions of said operating rotor corresponding to engagement of the various speed ratios which can be selected with the gear change, PA1 ratchet means for rotating the gear change operating rotor in one or in the other direction, said ratchet means comprising a single ratchet wheel rigidly connected to the operating rotor and a single operating lever swingably mounted on an intermediate support member which is in turn rotatably mounted around the axis of the operating rotor, said operating lever having an active end defining a pair of opposed teeth adapted to cooperate with said ratchet wheel for operating rotation in one direction or, respectively, in the other direction of said wheel and perform consequent gear change up shifting or down shifting selection. PA1 a support body intended to be fixed onto the bicycle handle bar, PA1 a gear change operating rotor, rotatably mounted in the support body and carrying winding up means of a gear change flexible control cable, PA1 indexing means carried by the operating rotor and by the support body, adapted to cooperate therebetween so as to define a plurality of steady positions of said operating rotor corresponding to engagement of the various transmission ratios which can be selected with the gear change, PA1 ratchet means for rotating the gear change operating rotor in one or in the other direction, said ratchet means comprising a single ratchet wheel rigidly connected to the operating rotor and a single operating lever swingably mounted on an intermediate support member which is in turn rotatably mounted around the axis of the operating rotor, said operating lever having an active end defining a pair of opposed teeth adapted to cooperate with said ratchet wheel for operating rotation in one or in the other direction, respectively, of said wheel and perform consequent up shifting or down shifting selection of the various gear change speeds,
A control device of the above disclosed type is shown for example in German Patent application DE-A-3136922. This known solution is related to an application for a racing bicycle and employs the support body of one of the brake control levers of the bicycle as the support body also for the gear change control device. Further, in this known solution a gear is provided for, acting both as the ratchet wheel of the ratchet mechanism, and as indexing toothed wheel, cooperating with a stop pawl for providing reference of the various operative positions of the gear change. This solution is thus difficult to be put into practice, since the two above disclosed functions would require different conformations of the toothed wheel. Moreover, the position of the operating lever, when same is inoperative, is not exactly defined, which makes the device hardly applicable in practical terms and subjected to failures.
Lastly it is to be pointed out that in the application onto the handle bar of a racing bicycle according to the above mentioned prior document, the operating lever is rotatable around an axis which is parallel to the pivoting axis of the brake control lever, which does not allow comfortable manoeuvring by the cyclist.
In recent years, a tendency has more and more developed to provide gear change control devices which on one hand are provided with a high operation efficiency, and on the other hand enable the cyclist to perform operation in an easy and quick way, without abandoning firm grasp of the handle bar. This need is particularly felt in the case of racing bicycles, since it is required that the cyclist can pay all his attention on the competition, as well as in the case of climbing bicycles (or "mountain-bikes"), wherein steady gripping of the handle bar is necessary for ensuring the equilibrium on uneven ground.
In the attempt to satisfy the above needs, several types of change gear control devices have been proposed in the past, sometimes in an integrated form with the brake control device. Devices of this type are shown for instance in U.S. Pat. No. A 4,100,820 and U.S. Pat. No. A 4,132,926. These documents show an assembly wherein the gear change control device comprises an operating lever projecting through a slit from the support body and having its end within the body which is rotatably mounted in the support body and is used for winding up the gear change flexible control cable. This member is subjected to the action of a friction mechanism which is sufficient to oppose the usual spring which is associated with the gear change derailer, so as to guarantee that the gear change operating lever remains in the selected position. Such a solution is unsatisfactory mainly for two reasons. Firstly, nowadays the use of gear change control devices of the indexed type has become more and more popular, since enabling the cyclist to have a certain reference of the operating lever corresponding to the various speed ratios which can be selected. Secondly, the gear change operating lever which is provided for in said known device can not always be easily and conveniently operated by the cyclist. In particular, operation thereof can be difficult in one of the two directions of rotation of the lever and when the lever is to be operated starting from some of the different possible operative positions thereof.
Fundamentally the same drawbacks exist even in the case of other known devices, such as those shown in U.S. Pat. No. A 3,478,617, in European Patent application EP-A-352732 and in German patent application DE-A-3916919. These three last documents, additionally, show control devices in which the brake lever and the gear change operating lever are pivotally mounted around parallel axis, which involves, as already pointed out, an uncomfortable manoeuvring of the gear change, at least when the gear change lever must be rotated forwardly.
It has also been proposed (see European Patent application EP-A-371254) to provide an integrated brake and gear change control assembly in which the brake lever itself, which is able to rotate around two mutually perpendicular axis, can act also as the gear change operating lever. This solution however has the inconvenience of requiring the use of a complex mechanism constituted by a huge number of components.
It has also been proposed (see International Patent application PCT/GB90/00220) a control assembly wherein the gear change operating lever is separated from the brake lever but is articulated to the body of the brake lever. Even in this case, the pivoting axis of the gear change operating lever is parallel to the pivoting axis of the brake lever and operation of the gear change is not always easy. Furthermore, the same Applicant has already proposed, in Italian patent application TO91A000167 and in the corresponding European patent application 92830101.9, a control device of a bicycle gear change comprising a support body constituted by the same support body of the brake lever and a gear change operating rotor which is rotatably mounted within the support body and can be driven in one and in the opposite direction by means of two ratchet devices separated from each other. This device further comprises indexing means of the type set forth at the beginning of the present specification. Each of the two ratchet devices comprises an operating lever articulated onto an intermediate support element which is in turn rotatably mounted around the axis of the operating rotor. Each ratchet device further comprises first resilient means urging the respective operating lever towards a rest position wherein one tooth carried by the operating lever is spaced apart from the respective ratchet wheel, and second resilient means, having a load greater than the load of the first resilient means, which are always urging the respective intermediate support member towards a same limit stop position wherein the operating lever can be easily reached.
The above device previously proposed by the Applicant is fully satisfactory under the operative point of view by virtue of a series of advantages: firstly, after each operation, the lever of each ratchet device is set again in the same position, which can be easily reached by the fingers of the cyclist's hand without any need of abandoning a correct grip of the handle bar. Secondly, each of the said levers is operable by a single operation so as to produce shifting even through several speed ratios. Further, in the application shown in the above-referenced patent document of the same Applicant, which is related to a racing bicycle, the axis of the gear change operating rotor is parallel to the longitudinal direction of the bicycle in the mounted condition, which enables positioning of the gear change up shifting, and, respectively, down shifting levers in the most suitable locations for easy handling thereof by the fingers of the cyclist's hand. This arrangement further allows passage of the operating cable inside or in close proximity of the handle bar tube.
In a subsequent patent application of the same Applicant (Italian patent application n. TO92A000316 of 07.04.1992), which is unpublished at the filing date of the present application, an improvement of the previously proposed device has been presented, wherein the support body of the device is not the support body of the brake operating lever, so as to enable convenient application of the device itself even onto bicycles of the "mountain-bike" type.